Boring bar



Nov. 4, 1947. R. ,L. MEALEY BORING BAR Filed Oct. 5, 1944 3 Sheets-Sheet l .Ik 1M D m 3 R NN 8 2. Q

R, L. MEALEY BORING BAR Filed Oct. 5', 1944 3 Sheets-Shet 2 gwue/wtoo 4 Raymond L MEfllE mwm jnm Mm .JR

Nov. 4, 1947.

R. L. ME ALEY BORING BAR "Filed Oct. 5, 1944 3 Shgets-Shegt 3 Patented Nov. 4, 1947 UNITED STATES PATENT OFFICE BORING BAR Raymond L. Mealey,,Watervliet, N. Y. Application October 5,1944, Serial No. 557,347

(Granted under the act of March 3, 1883, as

8 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to a boring bar, more particularly to a contour boring bar.

In the design of chambers for large caliber gun tubes, it has been found desirable to adopt a chamber having a cone shaped throat on each end of such chamber. To one skilled in the art it is obvious that the construction of such a chamber is not readily adaptable to modern mass production methods when utilizing present day boring equipment. Various attempts have been made in the past to adapt special boring bars to produce 'a chamber having both ends tapered. However,

such boring bars have been far from successful so that the boring of such chamber had to be accomplished on a lathe or with the expensive and slow operating built-up reamers on special boring machines. Obviously such a procedure was exceedingly slow and the accuracy of the completed chamber depended largely upon the skill of the operator.

Accordingly, it is an object of this invention to provide a contour boring bar which can be readily adapted to boring irregularly shaped surfaces in tubular members.

A particular object of this invention is to provide a contour boring bar constructed to produce irregularly shaped chambers in tubes of large caliber guns.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodimerit as shown in the accompanying drawings in which:

Fig. 1 is a, side elevational view of the contour boring bar.

Fig. 2 is an enlarged partial side elevational View of the boring bar shown in Fig. 1 shown partly in longitudinal section.

Fig. 3 is a cross sectional view taken along the plane 33 of Fig. 2.

Fig. 4 is an enlarged side elevational detail view of the cam bar showing a top view of the cam slots.

Fig. 4a is a view similar to Fig. 4 but showing a side elevational View of the cam slots.

Fig. 5 is a side elevational view of the connecting bar partly in section.

Fig. 6 is a side elevational View of the split bushing.

Fig. 7 is a front elevational view of Fig; 6.

amended April 30, 1928; 370 0. G. 757) Fig. 8 is a front end view of the cam bar extension.

Fig. 9 is a side elevational view of the cam bar extension.

Fig. 10 is a rear end view of cam bar shown in Fig. 4.

Fig. 11 is a cross sectional view taken along the plane ll-ll of Fig. 411.

Fig. 12 is a cross sectional view taken along the plane l2-I2 of Fig. 4a.

Fig. 13 is an enlarged detail view partly in longitudinal section of the tool bit holder showing the tool bit secured within such holder.

Fig/141s a side elevational view showing the mounting of the gun tube with the axis of such tube in alignment with the axis of the boring bar.

The contour boring bar to be presently described in detail is preferably utilized with a horizontal boring mill having both a quill and spindle feed. .The boring machine, however, should pref erably be capable of producing a spindle feed somewhat in excess of the quill feed. The ratio of quill feed to spindle feed must, of course, be taken into consideration in the design of the contour boring tool as will be later explained.

This invention essentially comprises a boring bar rotatably supported in a suitable bearing and secured to the quill of a horizontal boring mill. Such boring bar supports two oppositely disposed tool bits which are utilized to bore the chamber. The tool bit holders are connected to a cam bar contained within the hollow interior of the boring bar. The cam bar is connected to the spindle of the horizontal boring machine. The feed of the spindle however is preferably greater than the quill feed so that there is produced a relative movement of the spindle with respect to the quill. Thus the cam bar will move relative to the boring bar. The cam grooves provided in the cam bar force the tool bits inwardly or outwardly in accordance with the shape of such cam grooves to produce the desired contour of the chamber in the gun tube.

. There is shown in assembled relation in Fig. l

a contour boring bar I embodying this invention.

of such bar, as shown in Fig. 1, by a plug 8. Plug 8 is secured in the end of axial hole 2 as by threads 9. Two rectangular radial slots 4 oppositely disposed to one another are provided in boring bar I slightly to the left of the juncture of the large and small diameters of boring bar I as viewed in Fig. 2. Slots 4 are provided to slidably accept tool bit holders III to be later described. An annular flange 5 (Fig. 2) is welded to the left end of bar I to provide means for connecting bar I with a quill 53 of a horizontal boring machine. Flange 5 is secured to quill 53 by suitable bolts 5 and a key I.

Bar I is rotatably supported in a fixed bearing I! located slightly to the left of tool bit holders I3 as shown in Figs. 1 and 2. Bearing II is secured to a substantial base (not shown) by bolts I2. Bearing II is a substantial cast member comprising a lower base portion l3 and an upper cap portion I4. An axially split bushing I5 rests within bearing II and surrounds bar I. Bushing I5 (Figs. 6 and 7) is provided with integral flanges I5 on each side thereof to retain such bushing within bearing I I and is preferably constructed as described to facilitate assembly of bar in bearing I. Cap I4 is secured to lower bearing member I3 by bolts I6. Thus cap I4 secures split bushing I5 within bearing II. A ring IT (Fig. 2) of suitable gasket material is placed adjacent each side'of split bushing I5. A gasket retaining ring I8 is then placed adjacent ring [7. Each gasket and retaining ring is secured to bushing I5 by a plurality of equally spaced screws I3. Such screws are screwed into suitably threaded holes 2| in split bushing I5, Fig. 6.

The cam bar 23 is a substantially cylindrical member which is slidably insertable in axial hole 2 of bar I. The left end of cam bar 20 as shown in Fig. 4 is provided with a cylindrical shank 2.2 of substantially reduced diameter. The shank 22 is inserted into a connecting bar 50, as will be later described. Cam bar 2|] is provided with four longitudinal recesses 23 forming two longitudinally and radially extending fins 23a and 23b. Such recesses are equally disposed with respect to the axis of bar 20 and are of segmental cross section, the sides of such recesses being parallel to the vertical and horizontal axes of the cam bar as shown in Fig. 4a. Cam slots 24 are provided in the horizontal surfaces of each of recesses 23 as shown in Figs. 11 and 12. The recesses 23 and the cam slots 24 thus define a pair of substantially T-shaped ribs on opposite sides of cam bar 23, extending longitudinally thereof and projecting radially from the central body portion of the cam bar. Cam slots 24 are provided to advance or retract tool bit holders I3 as will be later described.

The cam bar 23 is connected to a spindle ID of the horizontal boring machine by the connecting bar 30 (Fig. 5). Connecting bar 60 is a rod-like member and on the left end of such bar there is provided a tapered shank 25 which engages the walls of a corresponding tapered hole H in spindle I3. The right end of bar 60 as shown in Fig. 5 is provided with an axial hole 23 of suilicient depth to accommodate the shank portion 2?. of cam bar 29. Connecting bar 63 is secured to shank 22 of cam bar 20 by a tapered shear pin 2"I. Such pin is inserted into a suitably tapered hole 23 which passes through both bar 55 and shank 22.

The tool bit holders I3 (Fig. 13) are substantially rectangular members. The lower. end of each tool bit holder III as shown in Fig. 3 is bifurcated forming two oppositely disposed lugs 23. A transverse hole 30 is provided in each lug 23 and such holes are in alignment. A pair of rollers 3| are each rotatably secured to the tool bit holder I0 by a stud 32 inserted in the holes 30 in lugs 23. Rollers 3| are placed adjacent the inside faces of lugs 29 as shown in Fig. 3. Studs 32 are secured to each lug 29 as by a pin 33.

The top of tool bit holder I0 is of pyramidal shape as shown in Figs. 3 and 13 and a substantially rectangular vertical recess I0a is provided in the top of such tool bit holder to receive a tool bit 35. Tool bit 35 is retained within such recess by a clamp 36. Clamp 36 is a rectangular member and is placed within a rectangular recess 31'provided on one side of tool bit holder -Ill. As recess Ifla communicates with recess 31, clamp 36 will bear against tool bit 35 to retain such tool bit therein. Clamp 36 is secured to holder II] by a plurality of screws 33.

Tool bit 35 is further secured within recess 34 against displacement by a tapered shear pin 39. Tapered pin 39 is inserted in a transverse hole 40 having a taper corresponding to that of pin 39. A screw 4| is provided obliquely displaced in holder II] as shown in Fig. 13 and engaging tool bit 35 to act as a retainer in the event of breakage of shear pin 39. Transverse screws :22 and 43 communicating with recess 34 from the outside of holder I0 secure tool bit 35 against sideways displacement.

Tool bits 35 contained within holder III are preferably carbide tipped. By the use of such carbide tipped tool bits greatly increased cutting life can be expected resulting in reduced down time for resharpening and resetting of such tool bits. Tool bit holders I0 are inserted within slots 4 in such fashion that when cam bar 20 is inserted into boring bar I from the left end thereof, as viewed in Fig. 1, each pair of cam slots 24 engages each pair of inwardly disposed rollers 3| on holder II). Cam bar 20 is then pushed to the right as shown in Fig. 1 as far as possible by connecting bar 60. The right end of cam bar 23 then projects beyond the right end of boring bar I so that a cam bar extension 44 may be secured to the end of such bar by screws 45.

Extension 44 is mounted on the end of cam bar 20 to provide an effective oil seal at the forward end of bar I and comprises a cast member as shown in Fig, 8 havin an integral cylindrical flange 43. A gasket 41 (Fig. 2) is placed adjacent flange 46. A ring 48 is then placed adjacent gasket 4"I and both ring 48 and gasket 41 are secured to flange 46 by a plurality of evenly spaced bolts 49.

A split bushing 65 surrounds the bar I in bearing relation near the forward end thereof as shown in Figs. 1 and 14. Such bushing is arranged to be expanded against the bore of the gun tube 52 by a tapered screw 55. Bushing B5 is provided to support the forward end of bar I conventionally with respect to the axis of tube 52.

An indicating mark I54 (Fig. 14) is provided on the periphery of boring bar I to indicate proper longitudinal alignment with the end of gun tube 52 for the beginning of the boring operation. To properly position tool bits 35 with respect to the start of the cut to be made in a chamber 6| of a gun tube 52 (Fig. 14) a locating rod 537 (Fig. l)

is provided. .Such rod communicates with a radial hole 54 provided thru extension bar 66, passing thru a suitable hole in bar I to enter hole 54 in bar 60. When tool .bit 35 is properly positioned, rod 53 is removed and hole fi l is sealed by suitable plugs 55 screwed into threads 56 at each end of such hole.

To produce contour boring of a workpiece such as the chamber 6! in a gun tube 52, as shown in Fig. 14, such tube is supported at each end in suitable mounts 62 and 63 respectively as shown in Fig. 14 so that the axis of tube 52 is in exact alignment with the axis of bar I. Tool bit 35 is then aligned with a suitable starting point in chamber 6| such as the rear edge of such chamber by means of the indicating mark 65 as above described. The quill and spindle are then set in motion and tool bit 35 is then fed into the Work. The ratio of feed of quill 5!} with respect to spindle feed for this particular application is .01" per minute to .015" per minute. Thus it is seen that cam bar 20 advances .005" per minute faster than bar l. Greater feed of cam bar 2!] is necessary so that cam bar 26 progresses with respect to tool holders l0 and thus tool bits 35 are moved. radially, producing a contour within tube 52 corresponding to the shape of cam track 24. Thus as cam bar 2% progresses into gun tube 52 more rapidly than boring bar l, tool bits 35 will be forced to follow cam tracks 24 through the connection of tool bit holders H] to such cam tracks by the rollers 3!. It should be mentioned, here that any ratio of feed of the quill to the feed of the spindle can be utilized but that such ratio will of course govern the layout of cam tracks 2d.

From the foregoing description it is readily apparent to one skilled in the art that a contour boring bar is hereby provided which will accurately and conveniently accomplish boring of an irregularly shaped contour. It is desired to point out that the boring bar described herein is not necessarily limited to the boring of chambers of gun tubes for larger caliber guns. Such bar can obviously be readily adapted to boring any irregularly shaped interior of any workpiece on a horizontal boring machine.

I claim:

1. The combination in a boring machine having a rotating quill and spindle with the quill having a different feeding rate than the spindle comprising, a, hollow tube having one end thereof secured to the quill of the boring machine, a tool holder supported in said hollow tube for generally radial movement and projecting into the interior thereof, a cam bar disposed within said tube having one end secured to the spindle of the boring machine, said cam bar being provided with a longitudinal groove therein which varies along its length in radial position with respect to the axis of said tube, and a roller on said tool holder engaged in said groove, all adapted and arranged whereby a desired radial movement of said tool holder in response to longitudinal movement of said cam bar relative to said tube is produced through the difference in quill feed and spindle feed.

2. In a boring bar, an elongated tubular bar having a central longitudinal axis, and an aperture in its wall non-circular in cross section and extending radially of said axis, a tool holder slidably fitting said aperture and translatable therealong radially of said axis, a cam bar fitting within said tubular boring bar and translatable longitudinally therealong, said cam bar being shaped to form a wall extending longitudinally .of the axis of cam bar, there being a channel in said wall extending longitudinally therealong said channel having its parallel side walls of varying distances from said axis, and follower means fittingbetween the side walls of said channel and connected with said holder to positively move said holder in each direction radially of said tubular bar upon relative axial translation of said bars.

3. The combination recited in claim 2, said channel having an axial extent less than that of the corresponding chamber of thebore of a tube to be bored, said cam bar being adapted to be translated axially along said tubular bar in timed relation with but at a rate less than the rate of translation of said tubular bar along said tube to be bored.

4. A boring bar comprising an elongated tubular bar having a longitudinal bore concentric of the axis of said bar, a tool holder slidably fitting a non-circular aperture in the wall of said bar and translatable therealong substantially radially of said axis, a cam slidably fitting said bore and translatable axially therealong, said cam having a fin extending radially and axially of and within said bore, there being a channel in each side wall of said fin, the distance of the parallel side walls of each channel from said axis, varying symmetrically in accordance with the desired contour of the bore of a tube to be bored, said holder having a bifurcated inner end straddling said fin and means on each bifurcation slidably fitting within a respective channel, said bar and cam being adapted for relative axial translation whereby to effect positive movement in both directions, of said holder radially of said bar.

5. In a boring bar, an elongated tubular bar having a longitudinal bore concentric of the axis thereof, there being a pair of aligned apertures through diametrically opposite wall portions of said bar substantially intermediate the ends thereof, a tool holder fitting each said aperture and guided thereby for translation radially of said axis, and a cam slidably fitting said bore and translatable axially therealong, said cam including a pair of diametrically opposed radial and longitudinally extending fins each having a channel in its opposite side walls, the distance of said Walls from said axis varying in accordance with the desired internal bore of a tube to be bored, each said holder having a bifurcated end straddling a respective fin and engaging the channels therein, whereby, on relative axial translation of said bar and cam, said holders are positively translated in each direction of radial movement.

6. In a cam for a boring bar, said cam comprising an elongated bar having a radial fin defining a longitudinally extending wall, there being a channel in said wall whose parallel sides vary in distance from the axis of said bar in accordance with the desired internal contour of a tube to be bored.

'7. In a cam for a boring bar, said cam comprising an elongated bar having a fin extending radially and longitudinally of said bar to define a pair of opposed parallel side Walls, there being a channel in each said wall, each said channel having parallel side walls whose distances from the axis of said cam vary symmetrically in accordance with the desired internal contour of a tube to be bored.

8. A cam for a boring tool, said cam comprising an elongated bar having first and second diametrically opposite fins each extending radially 7 8 and longitudinally of said barand each having 7 parallel side walls, the walls of each fin having UNITED STATES PATENTS a channel therein, the parallel side walls of each Number Name Date channel varying symmetrically in distance from 3 5 Oy n Sept. 20, 1932 the axis of said bar, in accordance with th de- 5 8 Young Jan. 14, 1941 sired internal contour of a tube to be bored. 1,360,444 ROline B11 1920 RAYMOND L. MEALEY. FOREIGN P TENTS REFERENCES CITED Number untry Date 4 5 0 The following references are of record in the 10 Germany Dec 2 1888 file of this patent: 

